I have seen articles that misrepresent a Flex Cluster, even this book Expert Oracle RAC 12c which is written by people who know better (Oracle ACE directors, an OCM, an Oak Table member) gets it wrong, because of a reliance on beta documentation.

One often sees requests for test cases, typically when a user has a SQL performance issue. So many users appear to have problems with producing a suitable test case that Uncle Oracle provides routine to automate this. There are no longer any excuses for not providing a test case. Here is an intro to how to do it (code tested on 11.2.0.3 and 12.1.0.1).

The inverted table format can deliver fast and flexible query capabilities, but is not widely used. ADABAS is probably the most successful implementation, but how often do you see that nowadays? Following is a description of how to implement inverted structures within a relational database. All code run on Oracle Database 12c, release 12.1.0.1.

There are three restrictions on indexing and partitioning: a unique index cannot be local non-prefixed; a global non-prefixed index is not possible; a bitmap index cannot be global. Why these limitations? I suspect that they are there to prevent us from doing something idiotic.

I see posts on Oracle related forums about various releases (anything that isn't 11.x or 12.x) being "unsupported". This is wrong. Of course you should upgrade any 9i or 10g databases, but you don't have to.

In this post, I will demonstrate a new feature introduced in 12c : In database archiving. It enables you to archive rows within a table by marking them as invisible. This is accomplshed by means of a hidden column ORA_ARCHIVE_STATE. These invisible rows are not visible to the queries but if needed, can be viewed , by setting a session parameter ROW ARCHIVAL VISIBILITY.

When you create a PDB, the database automatically creates and starts a service inside the CDB.The service has the same name as the PDB. It is possible that the name of the service will collide with an existing service name which is registered with the same listener. For example if two or more CDBs on the same computer system use the same listener, and the newly established PDB has the same service name as another PDB in these CDBs, then a collision occurs.

You must not attempt to operate a PDB that causes a collision with an existing service name.

Top 12 Features of Oracle 12C Summarized. This article is also available at www.ondemanddb.com
Summary: The Oracle 12C means different things to different people. It all depends on which areas you are looking at, as there are improvements in many areas. Summarized below is the list of Top 12 Features of Oracle 12C as I see it. I have summarized below, the top 12 which I found interesting.